Humidifiers are used in both industrial and domestic applications to condition the air so that the relative humidity of the air falls within a comfortable range particularly during seasons when the air is very dry. Common to most humidifiers is the use of a humidifier pad or wick which disperses water so that the water may be evaporated into a moving stream of air which is circulated through a house or industrial area to humidify the air. In most applications, the water used to feed a humidifier has some degree of hardness, which causes caking of the humidifier pad or wick and associated parts with mineral deposits and the like. It is therefore necessary to clean a humidifier on a regular basis to prevent an undesirable buildup of deposits in the humidifier and maintain the proper working efficiency of the humidifier. A week acid solution may be used to break up or dissolve the deposits, however, with a wick type humidifier pad the cloth material degenerates with repeated washings.
Other types of humidifier pads such as the common polyurethane foam type are also subject to degeneration because the polyurethane foam undergoes hydrolytic aging and, as a result, the foam material deteriorates rapidly to give only one or two seasons of use. In addition, cleaning problems arise because the mineral deposits tend to collect in the inner portion of the foam pad thereby making it difficult to remove such deposits and, as a result, cut down on the efficiency of the humidifier. A further problem associated with the use of foam type humidifier pads is that the foam is not self-supporting therefore a stainless steel wire cage or the like is required to support the pad in the humidifier and, consequently, the cage itself becomes caked with mineral deposits, thereby making replacement of the humidifier pad difficult.
In foamed humidifier pads, particularly those made from polyurethane foam, the prescribed pore size has been found to vary from pad to pad so that a variance in the humidifying efficiency of each pad results. This type of variance may become critical in industrial applications because of undesirable overworking of humidifier units if the efficiency drops.
The humidifier pad according to this invention has been designed to overcome these problems. The humidifier pad is made from a flexible, preferably plastic material, comprising a body portion with two opposing surfaces. The body portion has a plurality of unobstructed openings which allow communication between one of the surfaces and the other where the cross-sectional area of the openings is sufficient to permit a water film to span the openings as the respective openings emerge from the water bath. A plurality of projections may extend from at least one of the surfaces, the projections being needle-like or of other configurations such as continuous ribs extending beyond the surfaces to increase the surface area of the water film to be evaporated. The humidifier pad may be molded to form any type of structure such as the typical drum unit wherein one or more layers of the humidifier pad may be placed one within the other to form a desired drum wall thickness to disperse the required amount of water.
The plastic material used in forming a humidifier pad according to this invention should be flexible with some degree of resiliency so that the pad essentially retains its shape. Preferably the plastic material so used should be resistant to attack by weak acid solutions so that cleaning of a humidifier pad is easily done to break up and dissolve mineral deposits on the element. Also, during the cleaning step the flexible pad may be flexed or deformed to break the mineral deposits off the body portion. The broken-up mineral deposits may be easily removed due to the fact that all surfaces on any one layer of the humidifier pad are exterior. A wide range of plastic materials are available which may be used to form the humidifer pad and there are materials available which are substantially resistant to hydrolytic aging and, as a result, if properly cleaned, may be used in a humidifier for several seasons. Also, the pore size in the humidifier pad may be closely controlled due to the pad being preferably made by a plastic molding or extruding process, thereby resulting in a product with a substantially consistent pore size. Materials used in forming a drum-shaped humidifier pad are chosen on the basis that the worked material retains its shape and does not sag so that means may be provided on the drum for mounting the drum-shaped pad in a humidifier, eliminating the need for a stainless steel wire cage or the like.